Postgres FM

Tip: watch on YouTube. Since episode 193, the video shows charts and illustrations as we talk. https://www.youtube.com/watch?v=gf8e3JkQ_8M

Nik is joined by Kirk Wolak to discuss what a random UUIDv4 primary key really costs compared with a time-ordered UUIDv7 or an int8 key on Postgres 18 — index size, WAL and full-page writes, insert rate once the index outgrows memory — and what DBLab Forge found when it ran the experiment.
 
Here are some links to things they mentioned: 
Times are podcast times of the first mention.

Main link

• [00:00:34] UUIDv4 vs UUIDv7 vs int8 primary keys on Postgres 18 (DBLab Forge brief, PostgresAI) https://console.postgres.ai/shared/brief/9fffe2da-00c1-470b-a79d-a210ae2306bc

Hacking sessions

• [00:00:51] Hacking Postgres 101: ULID function (Postgres.TV, 2023) https://www.youtube.com/watch?v=YPq_hiOE-N8
• [00:00:51] Hacking Postgres sessions with Andrey, Kirk and Nik (YouTube playlist, PostgresTV) https://www.youtube.com/playlist?list=PLH8y1BNPAKjKDdJA7sDmFWUkbbYux3TRz

Episodes

• [00:05:53] Our previous episode with Kirk, also built on DBLab Forge: Dump/restore done. Now what? https://postgres.fm/episodes/dump-restore-done-now-what

Postgres

• [00:01:34] Commit adding uuidv7() to Postgres 18 (78c5e141e9c1, 2024-12-11) https://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=78c5e141e9c1
• [00:04:16] UUID functions, uuidv7() and uuid_extract_timestamp() (docs) https://www.postgresql.org/docs/18/functions-uuid.html
• [00:20:42] full_page_writes (docs) https://www.postgresql.org/docs/current/runtime-config-wal.html#GUC-FULL-PAGE-WRITES
• [00:25:01] wal_compression, lz4 and zstd (docs) https://www.postgresql.org/docs/current/runtime-config-wal.html#GUC-WAL-COMPRESSION
• [00:31:07] pg_stat_io (docs) https://www.postgresql.org/docs/current/monitoring-stats.html#MONITORING-PG-STAT-IO-VIEW

Standards and ID schemes

• [00:01:20] RFC 9562, Universally Unique IDentifiers (UUIDv7) https://www.rfc-editor.org/rfc/rfc9562
• [00:28:05] ULID spec https://github.com/ulid/spec
• [00:41:29] Snowflake ID (Twitter) https://github.com/twitter-archive/snowflake
• [00:41:29] Sharding & IDs at Instagram https://instagram-engineering.com/sharding-ids-at-instagram-1cf5a71e5a5c

Articles, books and tools

• [00:05:34] Sequential UUID generators (Tomas Vondra, 2018) https://www.enterprisedb.com/blog/sequential-uuid-generators
• [00:05:59] Systems Performance, 2nd edition (Brendan Gregg) https://www.brendangregg.com/systems-performance-2nd-edition-book.html
• [00:12:25] fio https://github.com/axboe/fio
• [00:26:17] Amazon Aurora pricing (I/O charges) https://aws.amazon.com/rds/aurora/pricing/
• [00:32:53] UUIDv7 doesn't have the properties you think it does (Robert Alexander, 2026) https://alexsci.com/blog/uuidv7-is-weird/
• [00:32:53] Hacker News discussion of that article https://news.ycombinator.com/item?id=50211746

~~~

What did you like or not like? What should we discuss next time? Let us know via a YouTube comment, on social media, or by commenting on our Google doc!

~~~

Postgres FM is produced by:

• Michael Christofides, founder of pgMustard
• Nikolay Samokhvalov, founder of PostgresAI

With credit to:

• Jessie Draws for the elephant artwork
• Intro and outro music: our own arrangement of Apple Loops from GarageBand (royalty-free under the GarageBand licence)

Nik is joined by Kirk Wolak, Software Architect at KiraSoft, to discuss what a database still needs after pg_restore finishes and before it takes production traffic — what pg_dump and pg_restore leave behind, why autovacuum may not catch up in time, and how Postgres itself could do better.
 
Here are some links to things they mentioned: 
Times are podcast times of the first mention.

Hacking sessions

• [00:00:27] Hacking Postgres sessions with Andrey, Kirk and Nik (YouTube playlist, PostgresTV) https://www.youtube.com/playlist?list=PLH8y1BNPAKjKDdJA7sDmFWUkbbYux3TRz
• [00:00:27] Hacking Postgres website https://hacking.postgres.tv
• [00:00:27] Hacking Postgres Telegram group https://t.me/postgres_hacking

Episodes

• [00:00:27] Our previous episode with Kirk: GSoC B-Tree Merge https://postgres.fm/episodes/gsoc-btree-merge
• [00:03:23] Is pg_dump a backup tool? https://postgres.fm/episodes/is-pg_dump-a-backup-tool

pgsql-hackers

• [00:15:39] pg_restore --include-analyze proposal (Jian He, 2025) https://www.postgresql.org/message-id/flat/CACJufxGx_YLLxmnZVMuUApiVYqjKrydvEQqD3qxhwM6e0_8jrQ%40mail.gmail.com
• [00:30:13] ANALYZE after restore (Christopher Kings-Lynne, 2002) https://www.postgresql.org/message-id/GNELIHDDFBOCMGBFGEFOOEOPCBAA.chriskl%40familyhealth.com.au
• [00:31:55] Statistics Import and Export (PG18 statistics transfer) https://www.postgresql.org/message-id/flat/CADkLM%3DfzX7QX6r78fShWDjNN3Vcr4PVAnvXxQ4DiGy6V%3D0bCUA%40mail.gmail.com

Commits

• [00:04:39] Transfer statistics during pg_upgrade (adds statistics to pg_dump, PG18) https://github.com/postgres/postgres/commit/1fd1bd871012732e3c6c482667d2f2c56f1a9395
• [00:30:13] vacuumdb --analyze-only processes partitioned tables (Laurenz Albe, PG19) https://github.com/postgres/postgres/commit/6429e5b771dbb98aa56441677b79cdb58f6e1675
• [00:42:38] Set pd_prune_xid on insert (Melanie Plageman, PG19) https://github.com/postgres/postgres/commit/378a216187aea1b488ce60ed07dd1ac5c14a9984

~~~

What did you like or not like? What should we discuss next time? Let us know via a YouTube comment, on social media, or by commenting on our Google doc!

~~~

Postgres FM is produced by:

• Michael Christofides, founder of pgMustard
• Nikolay Samokhvalov, founder of PostgresAI

With credit to:

• Jessie Draws for the elephant artwork
• Intro and outro music: our own arrangement of Apple Loops from GarageBand (royalty-free under the GarageBand licence)

Nik and Michael are joined by Álvaro Hernández to discuss sharding Postgres with Citus and StackGres, especially the new query router support that has been added very recently.
 
Here are some links to things they mentioned: 

• Álvaro Hernández https://postgres.fm/people/alvaro-hernandez-tortosa
• Ongres https://ongres.com
• Scaling Citus without limits: announcing Query Routers in StackGres https://stackgres.io/blog/scaling-citus-beyond-one-coordinator-announcing-query-routers-stackgres/
• Open-source Citus matches PlanetScale's Neki at 10M QPS on half the data nodes https://stackgres.io/blog/open-source-citus-matches-planetscales-neki-at-10m-qps-on-half-the-data-nodes/
• Postgres TV discussion about licenses with Álvaro https://www.youtube.com/watch?v=1rcbyIjA4gI
• Our episode with Sugu from Multigres https://postgres.fm/episodes/multigres
• Our (first) episode with Lev from PgDog https://postgres.fm/episodes/pgdog
• Citus https://github.com/citusdata/citus
• Citus goes fully open source (2022) https://www.citusdata.com/blog/2022/06/17/citus-11-goes-fully-open-source/
• 6M requests per second using ClickHouse (blog post by Alex Bocharov / Cloudflare) https://blog.cloudflare.com/http-analytics-for-6m-requests-per-second-using-clickhouse/
• pg_ash https://github.com/NikolayS/pg_ash
• 118 million queries per second on Neki (blog post by Florent Poinsard and Hirad Pourtahmasbi / PlanetScale) https://planetscale.com/blog/118-million-queries-per-second-on-neki
• Analyzing the Limits of Connection Scalability in Postgres (blog post by Andres Freund) https://www.citusdata.com/blog/2020/10/08/analyzing-connection-scalability/

~~~

What did you like or not like? What should we discuss next time? Let us know via a YouTube comment, on social media, or by commenting on our Google doc!

~~~

Postgres FM is produced by:

• Michael Christofides, founder of pgMustard
• Nikolay Samokhvalov, founder of Postgres.ai

With credit to:

• Jessie Draws for the elephant artwork

Nik and Michael are joined by Salma El-Sayed and Kirk Wolak to discuss their in-progress and very ambitious Google Summer of Code project around adding Btree Merge support to Postgres.
 
Here are some links to things they mentioned: 

• Salma El-Sayed https://postgres.fm/people/salma-el-sayed
• Kirk Wolak https://postgres.fm/people/kirk-wolak
• Google Summer of Code https://summerofcode.withgoogle.com
• PostgreSQL GSoC 2026 project ideas https://wiki.postgresql.org/wiki/GSoC_2026
• CMU Intro to Database Systems https://www.youtube.com/playlist?list=PLSE8ODhjZXjYMAgsGH-GtY5rJYZ6zjsd5
• Kirk, NIK, and Andrey’s Hacking Postgres sessions on YouTube https://www.youtube.com/playlist?list=PLH8y1BNPAKjKDdJA7sDmFWUkbbYux3TRz
• B-tree Index Bloat Reduction - Approach & Questions (Hackers thread, with patches) https://www.postgresql.org/message-id/flat/CANBEAPFq3YAOydjUS3xwcUG9L6e3WE5Z4nGPk_Q3RsjSFWTJNA%40mail.gmail.com
• B-tree merge visualizer https://kirkw.github.io/explainers/btree-merge-explainer.html

~~~

What did you like or not like? What should we discuss next time? Let us know via a YouTube comment, on social media, or by commenting on our Google doc!

~~~

Postgres FM is produced by:

• Michael Christofides, founder of pgMustard
• Nikolay Samokhvalov, founder of Postgres.ai

With credit to:

• Jessie Draws for the elephant artwork

Nik and Michael are joined by Sai Srirampur to discuss ClickHouse's new managed Postgres service.
 
Here are some links to things they mentioned: 

• Sai Srirampur https://postgres.fm/people/sai-srirampur
• ClickHouse Managed Postgres https://clickhouse.com/cloud/postgres
• ClickPipes https://clickhouse.com/cloud/clickpipes
• walshadow https://github.com/ClickHouse/walshadow
• pg_clickhouse https://github.com/clickHouse/pg_clickhouse
• ClickHouse PostgreSQL powered by Ubicloud https://www.ubicloud.com/blog/clickhouse-postgresql-powered-by-ubicloud
• Hacking Postgres logical decoding sessions https://hacking.postgres.tv/topics/logical-decoding/ 
• wal-rus https://github.com/ClickHouse/wal-rus
• pg_createsubscriber https://www.postgresql.org/docs/current/app-pgcreatesubscriber.html

~~~

What did you like or not like? What should we discuss next time? Let us know via a YouTube comment, on social media, or by commenting on our Google doc!

~~~

Postgres FM is produced by:

• Michael Christofides, founder of pgMustard
• Nikolay Samokhvalov, founder of Postgres.ai

With credit to:

• Jessie Draws for the elephant artwork

Nik and Michael discuss hot_standby_feedback — what it controls, whether and when read replicas should be changed to on, and other settings you can change to help too.
 
Here are some links to things they mentioned: 

• hot_standby_feedback https://www.postgresql.org/docs/current/runtime-config-replication.html#GUC-HOT-STANDBY-FEEDBACK
• hot_standby_feedback: experiments on PostgreSQL 17 (by Nik) https://console.postgres.ai/shared/brief/6018f69d-8975-48e3-8259-a72c77105572
• Best practices for Amazon RDS PostgreSQL replication (blog post) https://aws.amazon.com/blogs/database/best-practices-for-amazon-rds-postgresql-replication/
• log_autovacuum_min_duration https://www.postgresql.org/docs/current/runtime-config-logging.html#GUC-LOG-AUTOVACUUM-MIN-DURATION
• max_standby_streaming_delay https://www.postgresql.org/docs/current/runtime-config-replication.html#GUC-MAX-STANDBY-STREAMING-DELAY
• WAIT FOR LSN https://www.postgresql.org/docs/19/sql-wait-for.html
• transaction_timeout https://www.postgresql.org/docs/current/runtime-config-client.html#GUC-TRANSACTION-TIMEOUT
• Hot Standby Feedback should default to on in 9.3+ https://www.postgresql.org/message-id/flat/20121130190227.GJ3957%40awork2.anarazel.de

~~~

What did you like or not like? What should we discuss next time? Let us know via a YouTube comment, on social media, or by commenting on our Google doc!

~~~

Postgres FM is produced by:

• Michael Christofides, founder of pgMustard
• Nikolay Samokhvalov, founder of Postgres.ai

With credit to:

• Jessie Draws for the elephant artwork

Nik and Michael are joined by Shaun Thomas to discuss estimating work_mem, memory management in general, and writing an extension to help.
 
Here are some links to things they mentioned: 

• Shaun Thomas https://postgres.fm/people/shaun-thomas
• work_mem https://www.postgresql.org/docs/current/runtime-config-resource.html#GUC-WORK-MEM
• pg_stat_database https://www.postgresql.org/docs/current/monitoring-stats.html#MONITORING-PG-STAT-DATABASE-VIEW
• ALTER ROLE SET configuration_parameter https://www.postgresql.org/docs/current/sql-alterrole.html#SQL-ALTERROLE-PARAMS-CONFIGURATION-PARAMETER
• hash_mem_multiplier https://www.postgresql.org/docs/current/runtime-config-resource.html#GUC-HASH-MEM-MULTIPLIER
• Recent Postgres releases with 28 CVEs fixed https://www.postgresql.org/about/news/postgresql-186-1711-1615-1519-1424-and-19-beta-3-released-3365/
• Systemic Risks in the Managed PostgreSQL Industry (part 1 of 6, Mehmet Ince) https://mehmetince.net/part-1-6-systemic-risks-in-the-managed-postgresql-industry-extension-risks-are-real-exploiting-postgis-memory-corruption-bug-at-neondb-supabase-and-many-more/
• Improving Postgres Connection Scalability: Snapshots (blog post by Andres Freund) https://techcommunity.microsoft.com/blog/adforpostgresql/improving-postgres-connection-scalability-snapshots/1806462

~~~

What did you like or not like? What should we discuss next time? Let us know via a YouTube comment, on social media, or by commenting on our Google doc!

~~~

Postgres FM is produced by:

• Michael Christofides, founder of pgMustard
• Nikolay Samokhvalov, founder of Postgres.ai

With credit to:

• Jessie Draws for the elephant artwork

Nik and Michael are joined by Michael Malis, co-creator of pgrust, to discuss their Postgres rewrite, including reliability problems, compatibility testing, faster analytics, and a new JIT-compiled query engine.
 
Here are some links to things they mentioned: 

• Michael Malis https://postgres.fm/people/michael-malis
• pgrust https://github.com/malisper/pgrust 
• The four horsemen behind Postgres outages (blog post by Michael Malis) https://malisper.me/the-four-horsemen-behind-thousands-of-postgres-outages
• Rebuilding Postgres for faster analytics: batching, operator fusion, and SIMD (blog post by Michael Malis) https://malisper.me/how-we-made-postgres-hundreds-of-times-faster-the-query-engine/
• kani https://github.com/model-checking/kani
• Antithesis https://antithesis.com
• fsyncgate mailing list thread https://www.postgresql.org/message-id/flat/CAMsr%2BYHh%2B5Oq4xziwwoEfhoTZgr07vdGG%2Bhu%3D1adXx59aTeaoQ%40mail.gmail.com
• How AI Changes the Economics of JIT Compilers (blog post by Michael Malis) https://malisper.me/how-ai-changes-the-economics-of-jit-compilers/
• Umbra DB https://umbra-db.com

~~~

What did you like or not like? What should we discuss next time? Let us know via a YouTube comment, on social media, or by commenting on our Google doc!

~~~

Postgres FM is produced by:

• Michael Christofides, founder of pgMustard
• Nikolay Samokhvalov, founder of Postgres.ai

With credit to:

• Jessie Draws for the elephant artwork

Nik and Michael are joined by Radim Marek to discuss MVCC, including his recent article on how Postgres chose to implement it compared to other systems.
 
Here are some links to things they mentioned: 

• Radim Marek https://postgres.fm/people/radim-marek
• BoringSQL https://boringsql.com
• PostgreSQL's MVCC is bad. So is everyone else's (blog post by Radim) https://boringsql.com/posts/mvcc-bad-bad/
• PostgreSQL MVCC documentation https://www.postgresql.org/docs/current/mvcc-intro.html
• PostgreSQL Storage Internals series by Radim https://boringsql.com/guides/postgresql-storage-internals/
• PgQue https://github.com/NikolayS/pgque
• The next ten years of Postgres (talk slides by Álvaro Herrera) https://www.postgresql.eu/events/pgconfde2026/sessions/session/7744/slides/866/edb-keynote-pgconfde-2026.pdf
• Episode on RegreSQL https://postgres.fm/episodes/regresql
• DryRun MCP https://github.com/boringsql/dryrun

~~~

What did you like or not like? What should we discuss next time? Let us know via a YouTube comment, on social media, or by commenting on our Google doc!

~~~

Postgres FM is produced by:

• Michael Christofides, founder of pgMustard
• Nikolay Samokhvalov, founder of Postgres.ai

With credit to:

• Jessie Draws for the elephant artwork

Nik and Michael are joined by Tudor Golubenco, CTO of Xata, to discuss their architecture, progress, and open source tooling.
 
Here are some links to things they mentioned: 

• Tudor Golubenco https://postgres.fm/people/tudor-golubenco
• Xata https://xata.io
• Xata is now open source https://xata.io/blog/xata-is-now-open-source
• DBLab Engine https://postgres.ai/docs/database-lab
• pgstream https://github.com/xataio/pgstream
• Xata acquires Privacy Dynamics for advanced anonymization https://xata.io/blog/xata-acquires-privacy-dynamics
• Tonic AI https://www.tonic.ai
• A thousand Postgres branches for one dollar https://xata.io/blog/a-thousand-postgres-branches-for-1
• pgroll https://github.com/xataio/pgroll
• CloudNativePG https://github.com/cloudnative-pg/cloudnative-pg
• PGSimCity https://nikolays.github.io/PGSimCity
• DeltaX https://github.com/xataio/deltax

~~~

What did you like or not like? What should we discuss next time? Let us know via a YouTube comment, on social media, or by commenting on our Google doc!

~~~

Postgres FM is produced by:

• Michael Christofides, founder of pgMustard
• Nikolay Samokhvalov, founder of Postgres.ai

With credit to:

• Jessie Draws for the elephant artwork